PIER FOUNDATION SYSTEM FOR MANUFACTURED BUILDING STRUCTURES
A foundation system for a manufactured building structure includes a pier for attaching the building structure to a foundation.
Manufactured buildings and structures such as prefabricated homes and trailers are typically fabricated at a factory, and then transported to a site for installation on a foundation. Simple piers and other foundations supports have been used to support the manufactured structures at the installation site.
In the following detailed description and in the several figures of the drawing, like elements are identified with like reference numerals. The figures are not to scale, and relative feature sizes may be exaggerated for illustrative purposes.
An exemplary embodiment of a manufactured building structure 10 is illustrated in
The structure 10 may have a width of ten, twelve or fourteen feet in an exemplary embodiment, for each unit. Thus, for a double-wide unit, the nominal width may be twenty feet, twenty-four feet or twenty-eight feet, in this example. The length of the structure in an exemplary embodiment may vary from thirty six feet to sixty six feet.
In this exemplary embodiment, as depicted in
The housing structure is attached to, and supported by, the configuration of piers 40 and 50.
Also providing foundation support are the piers 50, each of which is attached to a chassis beam 14, and are depicted in further detail in
An exemplary embodiment of a GAD pier 50 is illustrated in
The exemplary pier 50 embodiment may also include a bottom plate 58, which in an exemplary embodiment may be a 12 inch square, ½ inch thick, steel plate, with corner holes 58A formed therein for securing the pier to a foundation bolt system.
In an exemplary embodiment, the lower plate 56 may be attached to the bottom plate 58 by a sandwich arrangement of bearings structures 60, 62 and 64, and bars 66, 68. The bearing structures may be fabricated of polyurethane, for example. By way of further example, bearing structures 60, 62 may be 1 inch thick by 2 inch wide by 8 inch long polyurethane blocks, and bearing structure 64 may be a 1 inch thick by 8 inch wide by 8 inch long polyurethane block. The polyurethane in an exemplary embodiment may conform to the following characteristics: free from voids and imperfections; elastic modulus between 200 psi and 1000 psi over a temperature range of −20 degrees F. to +120 degrees F.; modulus of rigidity between 10% to 33% of the elastic modulus over the temperature range; fraction of critical damping over temperature range of interest (e.g., −20 degrees F. to 120 degrees F.) for both axial and shear distortions not less than 30% of critical; tensile strength of 100 psi or greater; Brinell hardness of 10 or greater; not susceptible to significant creep; long term creep strains not exceeding three times normal elastic strains.
In an exemplary embodiment, the polyurethane bearing structures and the lower plate are captured between the bottom plate 58 and rigid plates 60, 62, 66 and 68. In an exemplary embodiment, the rigid plates 60, 62, 66, 68 are ½ inch thick by 2 inch wide by 8 inch long steel plates, with ½ inch diameter bolt holes formed at each end to receive the fastening bolts, as shown in further detail in
The pier 50 may be attached to a chassis beam 14 of the housing structure 10. In an exemplary embodiment, a pair of wood shims 84, 86 sandwich the beam 14, and in turn are captured between angle structures 80, 82. The angle structures 80, 82 may in an exemplary embodiment be fabricated of ⅜ inch thick steel, and have bolt openings formed therein to receive mounting bolts therethrough to secure the sandwiched assembly of the chassis beam 14, the wood shims 84, 86 and the angle structures 80, 82 together. The angle structures 80, 82 may also have bolt openings formed therein to receive bolts therethrough to secure the angle structures to the top plate 52. For example, the angle structure may have a ¾ inch diameter opening 82A and ½ inch diameter openings 82B formed therein. The top plate 52 has corresponding bolt openings formed therein at each corner to receive the mounting bolts which fasten the top plate to the angle structures and the chassis rail of the structure 10.
The footings 22 may be constructed on site. Alternatively, the footings 22 may be prefabricated, and then installed on the building site. For construction on site, the footing hole may be dug into the ground at the appropriate permanent location of the footing. Forms may be used to define the footing in some applications. For other sites, the hole is dug to the appropriate size and the hole walls define the footing size. The rods 110 may be augered into the ground to an appropriate depth, with ends exposed in the hole. Wet concrete may be poured into the hole, embedding the exposed ends of the rods in the wet concrete. The angled ends of the angle bolts 100 may be inserted into the wet concrete to the appropriate depth, using a template to position the bolts so that the spacing is correct to match the opening configuration in the bottom plate of the GAD pier 50.
In operation, the GAD piers 50 may function to allow some limited movement of the chassis rail 14 relative to the concrete footing 22, due to the bearings and bushings which will deflect or deform in response to shaking or movement of the earth due to earth tremors or earthquakes, or due to forces applied during high winds, while still maintaining a connection between the rail and footing. Thus, the GAD piers 50 may help to mitigate the effects of tremblers and high winds by providing some measure of flexible support to a securely anchored structure.
Although the foregoing has been a description and illustration of specific embodiments of the invention, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope and spirit of the invention as defined by the following claims.
Claims
1. A pier for a foundation system for a manufactured building structure, comprising:
- a top plate structure adapted for attachment to the manufactured building structure;
- a lower plate structure;
- a generally vertical rigid member attached between the top plate structure and the lower plate structure;
- a bottom plate structure attached to a foundation footing;
- a bearing structure for connecting the lower plate structure to the bottom plate structure and adapted to allow limited movement between the bottom plate structure and the lower plate structure in response to forces applied during seismic events and high winds.
2. The pier of claim 1, wherein said manufactured building structure includes a chassis rail, the pier further comprising a bracket structure for attaching the top plate structure to the chassis rail.
3. The pier of claim 1, wherein said bearing structure comprises a plurality of polyurethane bearing structures sandwiching the lower plate structure.
4. The pier of claim 3, wherein said plurality of polyurethane bearing structures includes a lower generally planar polyurethane structure for mounting against a bottom facing surface of the lower plate structure, and a pair of upper generally planar polyurethane structures for mounting against a top surface of the lower plate structure.
5. The pier of claim 4, wherein said bearing structure further comprises a pair of rigid plate members positioned on respective top surfaces of the pair of upper polyurethane structures, and a plurality of threaded bolt and nut pairs for securing the bearing assembly together and to the lower plate structure and the bottom plate structure.
6. The pier of claim 5, wherein the plurality of threaded bolts are passed through openings formed in said polyurethane structures.
7. The pier of claim 6, further comprising a plurality of annular bushings positioned between the threaded bolts and said polyurethane structures, said bushings fabricated of a softer material than said bearings.
8. The pier of claim 7, wherein said annular bushings are fabricated of lead.
9. The pier of claim 1, wherein the foundation footing comprises a concrete footing, the pier further including a set of threaded angle bolts each having an angle end portion embedded in the concrete footing and an exposed threaded end for securing the bottom plate to the concrete footing.
10. The pier of claim 1, wherein the generally vertical rigid member is fabricated of a hollow tube member.
11. The pier of claim 9, wherein the foundation footing further comprising a plurality of anchor rods protruding outwardly from the concrete footing and embedded in soil.
12. A foundation system for a manufactured building structure, comprising:
- a plurality of support piers positioned between a site ground surface and said building structure;
- a plurality of permanent foundation piers, each pier comprising: a top plate structure adapted for attachment to the manufactured building structure; a lower plate structure; a generally vertical rigid member attached between the top plate structure and the lower plate structure; a bottom plate structure attached to a foundation footing; a bearing structure for connecting the lower plate structure to the bottom plate structure and adapted to allow limited movement between the bottom plate structure and the lower plate structure in response to forces applied during siesmic events and high winds.
13. The system of claim 12, wherein said manufactured building structure includes a chassis rail, the pier further comprising, for each of said plurality of permanent foundation piers, a bracket structure for attaching the top plate structure to the chassis rail.
14. The system of claim 12, wherein said bearing structure comprises a plurality of rigid bearing structures sandwiching the lower plate structure.
15. The system of claim 14, wherein said plurality of rigid bearing structures includes a lower generally planar rigid bearing structure for mounting against a bottom facing surface of the lower plate structure, and a pair of upper generally planar rigid bearing structures for mounting against a top surface of the lower plate structure.
16. The system of claim 15, wherein said bearing structure further comprises a pair of rigid plate members positioned on respective top surfaces of the pair of upper polyurethane structures, and a plurality of threaded bolt and nut pairs for securing the bearing assembly together and to the lower plate structure and the bottom plate structure.
17. The system of claim 16, wherein the plurality of threaded bolts are passed through openings formed in said rigid bearing structures.
18. The system of claim 17, further comprising a plurality of annular bushings positioned between the threaded bolts and said rigid bearing structures, said bushings fabricated of a softer material than said rigid bearing structures.
19. The system of claim 18, wherein said annular bushings are fabricated of lead.
20. The system of claim 18 wherein said rigid bearing structures are fabricated of polyurethane.
21. The system of claim 12, wherein the foundation footing comprises a concrete footing, the pier further including a set of threaded bolts each having an exposed threaded end for securing the bottom plate to the concrete footing.
22. The system of claim 21, wherein the foundation footing further comprising a plurality of anchor rods protruding outwardly from the concrete footing and embedded in site soil.
Type: Application
Filed: May 31, 2006
Publication Date: Dec 6, 2007
Inventor: Gordon Snyder (Crestine, CA)
Application Number: 11/421,424